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Title:Equilibrium concentration of interstitials in aluminum just below the melting temperature
Author(s):Gordon, Craig Alan
Doctoral Committee Chair(s):Granato, A.V.
Department / Program:Physics
Subject(s):Interstitialcy Theory
non-contact electromagnetic acoustic transducer
Abstract:The Interstitialcy Theory offers a unified description of the solid, liquid, and amorphous states of condensed matter, including a direct criterion for the onset of melting. A major prediction of the theory is that the equilibrium concentration of interstitial defects should be only about an order of magnitude less than the vacancy concentration near the melting temperature. Of the various properties affected by the presence of interstitials, the shear modulus is known to be particularly sensitive. A non-contact EMAT technique of ultrasonic generation and detection was used to make high temperature measurements of the C44 and C' shear elastic moduli in aluminum. The results show a large C44 deviation just below the melting temperature and a much smaller effect for C', which is to be expected for interstitials in FCC crystals. The results are analyzed to give a detected interstitial concentration of 1.7 ± 0.6 x 10^4 just below the melting temperature of 933 K. This corresponds to a reasonable range for the interstitial formation enthalpy and entropy, and supports the prediction of the Interstitialcy Theory.
Issue Date:2000
Genre:Dissertation / Thesis
Other Identifier(s):4280354
Rights Information:©2000 Gordon
Date Available in IDEALS:2012-05-29

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